Good viscosity stability of latex compounds is important for production processes. The effect of additions of potassium laurate, zinc oxide and ammonium sulphate on the viscosity of a natural rubber latex concentrate were investigated using a full two-level factorial design. The main and interaction effects were found to be large and significant as calculated by Yates Algorithm. Thus all three vaiables jointly influenced the viscosity stability of latex compounds. When potassium laurate and ammonium sulphate were at the +l levels, the increases in viscosity of the latex compounds were found to be large and gelation took place on overnight maturation. The destabillising effect of the laurate has been intperpreted based on the results of radiotracer investigations on 14C-laurate soap adsoprtion on latex particles, which showed appreciable surface portein displacement by the aaded soap at high soap concentrations. A similiar interpretation is made- albeit less conclusively - when the nitrogen values of the cream fraction of latex which was treated with high laurate concentrations were examined. Further, the destabilising influence of ammonium sulphate on latex compounds is discussed together with some data showing the relationship between ammonia/ammonium concentrations and zinc oxide solubility as measured by a .65Zn-radiotracer method.